Three-phase saturated-core fault current limiter

Abstract

The saturated-core fault current limiter (SFCL) is widely used to limit the fault current. However, in the conventional SFCL structure, alternating current (AC) and direct current (DC) coils are wound on different loosely coupled cores. Owing to the leakage inductance, the traditional structure demonstrates relatively large demand for DC excitation power and excessive impedance during saturation. In this study, a new structure for winding closely coupled DC and AC coils on the same core in three phases is proposed to reduce the influence of leakage reactance on the SFCL performance. The leakage magnetic flux generated by both structures is analyzed by performing finite element analysis simulations and utilizing a magnetic field division method. The impedance of the limiter is measured at different DC currents and air gaps to optimize its dynamic performance. A fabricated prototype of the proposed limiter exhibits smaller steady-state losses and high current-limiting capability.